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Zenz, Ivo (2012): Quantification of the electrophilic reactivities of nitroalkenes. Dissertation, LMU München: Faculty of Chemistry and Pharmacy
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Abstract

While a large variety of nucleophiles (N and sN) have been characterized according to eq 1.3, the number of E parameters for electrophiles, and specifically for different classes of Michael acceptors remains relatively small. A goal of this work was to include the synthetically important trans--nitrostyrenes (Chapter 2) and aliphatic nitroolefins (Chapter 3) into our reactivity scale, by measuring the rates of their reactions with stabilized carbanions. The reactions of (E)-1-ethoxy-2-nitroethene with pyridinium ylides, and of (E)-N,N-dimethyl-2-nitroethenamine with stabilized carbanions will be discussed in Chapter 4. Considerable effort has been spent on the development of organocatalytic asymmetric Michael additions. The reactions of nitrostyrenes with ketones or aldehydes have been used as model reactions for probing the efficiency and selectivity of new organocatalysts. The kinetic of the reaction of trans--nitrostyrene with cyclohexanone catalyzed by pyrrolidine and benzoic acid has been investigated, and the individual rate orders have been determined in order to provide insight into the catalytic cycle (Chapter 5). Diazo compounds are common and versatile reagents in organic synthesis despite their hazardous nature. Therefore, the rates of reactions of diazo compounds with Michael acceptors (Chapter 6) have been studied in order to elucidate the degree of concertedness of these 1,3-dipolar cycloadditions, and to investigate if they can be described by eq 1.3.